An intersteller spacecraft far away from the influence of any star or planet is moving at high speed under the influence of fusion rockets (due to thrust exerted by fusion rockets, the spacecrafts is accelearting). Suddenly the engine malfunctions and stops. The spacecraft will
(a) immediately stops, throwing all of the occupants to the front
(b) begins slowing down and eventually comes to rest
(c) keep moving at constant speed for a while, and then begins to slow down
(d) keeps moving forever with constant speed